tree:   https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git kspp/memcpy/next-20210618/v0
head:   fd2aa2a169de8bde9502e7a2fc48cd03d4bfd996
commit: 21405e341f4b8742f8c6d8b91ad39348d7cf970f [58/82] fortify: Detect struct member overflows in memcpy()
config: powerpc64-randconfig-r004-20210618 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project d1baf2895467735ab14f4b3415fce204c0cc8e7f)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install powerpc64 cross compiling tool for clang build
        # apt-get install binutils-powerpc64-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git/commit/?id=21405e341f4b8742f8c6d8b91ad39348d7cf970f
        git remote add kees https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git
        git fetch --no-tags kees kspp/memcpy/next-20210618/v0
        git checkout 21405e341f4b8742f8c6d8b91ad39348d7cf970f
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=powerpc64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> lib/string_helpers.c:883:6: warning: no previous prototype for function '__read_overflow2_field' [-Wmissing-prototypes]
   void __read_overflow2_field(void) { }
        ^
   lib/string_helpers.c:883:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void __read_overflow2_field(void) { }
   ^
   static 
>> lib/string_helpers.c:885:6: warning: no previous prototype for function '__write_overflow_field' [-Wmissing-prototypes]
   void __write_overflow_field(void) { }
        ^
   lib/string_helpers.c:885:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void __write_overflow_field(void) { }
   ^
   static 
>> lib/string_helpers.c:889:6: warning: no previous prototype for function 'fortify_warn_write' [-Wmissing-prototypes]
   void fortify_warn_write(const char *func, size_t buffer_size, size_t write_size)
        ^
   lib/string_helpers.c:889:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void fortify_warn_write(const char *func, size_t buffer_size, size_t write_size)
   ^
   static 
   lib/string_helpers.c:896:6: warning: no previous prototype for function 'fortify_panic' [-Wmissing-prototypes]
   void fortify_panic(const char *name)
        ^
   lib/string_helpers.c:896:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   void fortify_panic(const char *name)
   ^
   static 
   4 warnings generated.


vim +/__read_overflow2_field +883 lib/string_helpers.c

   881	
   882	/* These are placeholders for fortify compile-time warnings. */
 > 883	void __read_overflow2_field(void) { }
   884	EXPORT_SYMBOL(__read_overflow2_field);
 > 885	void __write_overflow_field(void) { }
   886	EXPORT_SYMBOL(__write_overflow_field);
   887	
   888	/* Run-time warnings */
 > 889	void fortify_warn_write(const char *func, size_t buffer_size, size_t write_size)
   890	{
   891		WARN_ONCE(1, "%s: detected buffer (size %zu) overflowing write (size %zu)\n",
   892			  func, buffer_size, write_size);
   893	}
   894	EXPORT_SYMBOL(fortify_warn_write);
   895	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org